Electric vehicles, such as electric forklifts, golf carts, street vehicles and other means of transport utilizing electric motor control devices, typically employ what are known as analog foot pedal controllers. A basic component of an analog foot pedal controller is a potentiometer. In its most general sense, a potentiometer is really only a variable electric resistor. In particular, however, an analog potentiometer is an electromechanical device having a terminal connected to each end of a resistive element, and a third terminal connected to a moveable slider contact. An electric input (i.e. voltage) is divided as the moveable slider contact moves over the resistive element, thus making it possible to mechanically change the resistance. In an analog foot pedal controller, a foot pedal is mechanically linked to the moveable slider contact so that displacement of the foot pedal causes a displacement of the moveable slider contact. The displacement of the moveable slider contact then causes a change in the electric output at the third terminal of the potentiometer. This change in electric output is usually then transformed into a motor control signal that is usually a representative voltage signal, hence the term "analog." Additionally, "Hall effect" devices are sometimes also used to generate these representative analog signals. Generally, in a Hall effect device, a magnetic field is applied to a current carrying conductor to create an output voltage. By varying the magnetic field, the output voltage can be varied.
The use of analog potentiometer foot pedals is disadvantageous for several reasons. Firstly, because they depend upon a moveable slider contact to contact a resistive element, they are prone to physical wear and failure. Secondly, due to the nature of their location, i.e. usually at or near the operator's feet, they are prone to contaminates such as dirt or metal shavings from a factory floor that may cause the moveable slider contact to not make contact with the resistive element, or the contaminants may create a false contact in the resistive element leading to a false change in electric output.
Thus, it is apparent that a new type of foot pedal motor controller is desirable to replace the traditional analog potentiometer foot pedal. However, it is still desirable to provide an analog output signal because many new and currently operating vehicle's still employ analog potentiometer foot pedal systems.